// ******************************************************************************
// Spine Runtimes Software License v2.5
//
// Copyright (c) 2013-2016, Esoteric Software
// All rights reserved.
//
// You are granted a perpetual, non-exclusive, non-sublicensable, and
// non-transferable license to use, install, execute, and perform the Spine
// Runtimes software and derivative works solely for personal or internal
// use. Without the written permission of Esoteric Software (see Section 2 of
// the Spine Software License Agreement), you may not (a) modify, translate,
// adapt, or develop new applications using the Spine Runtimes or otherwise
// create derivative works or improvements of the Spine Runtimes or (b) remove,
// delete, alter, or obscure any trademarks or any copyright, trademark, patent,
// or other intellectual property or proprietary rights notices on or in the
// Software, including any copy thereof. Redistributions in binary or source
// form must include this license and terms.
//
// THIS SOFTWARE IS PROVIDED BY ESOTERIC SOFTWARE "AS IS" AND ANY EXPRESS OR
// IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
// EVENT SHALL ESOTERIC SOFTWARE BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES, BUSINESS INTERRUPTION, OR LOSS OF
// USE, DATA, OR PROFITS) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
// IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.
// ******************************************************************************

part of spine_core;

class SwirlEffect implements VertexEffect {
  static final PowOut interpolation = PowOut(2.0);
  double centerX = 0.0;
  double centerY = 0.0;
  double radius = 0.0;
  double angle = 0.0;
  double worldX = 0.0;
  double worldY = 0.0;

  SwirlEffect(this.radius);

  @override
  void begin(Skeleton skeleton) {
    worldX = skeleton.x + centerX;
    worldY = skeleton.y + centerY;
  }

  @override
  void transform(Vector2 position, Vector2 uv, Color light, Color dark) {
    final double radAngle = angle * MathUtils.degreesToRadians;
    final double x = position.x - worldX;
    final double y = position.y - worldY;
    final double dist = math.sqrt(x * x + y * y);
    if (dist < radius) {
      final double theta =
          interpolation.apply(0.0, radAngle, (radius - dist) / radius);
      final double cos = math.cos(theta);
      final double sin = math.sin(theta);
      position
        ..x = cos * x - sin * y + worldX
        ..y = sin * x + cos * y + worldY;
    }
  }

  @override
  void end() {}
}
